Vascular plant response to windthrow severity in Norway spruce–dominated Myrtillus site type forests in Estonia

Species composition and number of species in ground vegetation after windthrow varies depending on damage severity and management actions after a storm event. In this paper we seek to determine the changes in species composition depending on the severity of storm damage. The vegetation response was studied by comparing areas with different levels of windthrow damage (undamaged, partly damaged, totally damaged, and totally damaged and harvested) in Norway spruce–dominated forests in Estonia. A total of 108 herbal and shrub species were found in all areas. Species number was lowest in the control areas and highest in the harvested plots. The number of species that responded to disturbance severity, when compared to the control plots, increased during the second year of the two-year survey period. The groups of species responding to different degrees of storm severity and silvicultural treatments were identified. Early invasion after a storm was observed in the case of several species, such as Epilobium angustifolium, Rubus idaeus, and Ranunculus repens. All the ferns that responded to damage extent seemed to be most favoured in totally damaged areas. Rubus saxatilis showed the clearest response trend, with higher coverage in response to increasing wind severity.